Re: Unstable tests

On 04/05/18 16:38, Lee wrote:
> On 4/5/18, Keith Mendoza  wrote:
>> So again, at what point do we stop adding code to net-snmp because
>> ISP's are messing around as if they're doing us a favor by letting us
>> use their services?
> 
> Since people don't read the docs, how about adding a test to see if
> dns is borked; if it is link to a faq entry for possible ways to fix
> it.
> 
> verizon 'opt out of dns assistance' link:
>    https://www.verizon.com/support/residential/internet/home-network/settings/opt-out-of-dns-assist

How about the patch below? With this patch applied Net-SNMP developers can
make the tests pass easily by setting the NETSNMP_DNS_WORKAROUND environment
variable before running the tests and normal operation of snmpd is not
affected.

Thanks,

Bart.



Subject: [PATCH] snmplib: Avoid that test T070com2sec_simple fails due to DNS filtering

---
 snmplib/system.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/snmplib/system.c b/snmplib/system.c
index d7f06f74087f..28b832352247 100644
--- a/snmplib/system.c
+++ b/snmplib/system.c
@@ -762,6 +762,24 @@ netsnmp_validator_context(void)
 int
 netsnmp_gethostbyname_v4(const char* name, in_addr_t *addr_out)
 {
+    if (getenv("NETSNMP_DNS_WORKAROUND")) {
+        /*
+         * A hack that avoids that T070com2sec_simple fails due to the DNS
+         * client filtering out 127.0.0.x addresses and/or redirecting DNS
+         * resolution failures to a web page.
+         */
+        if (strcmp(name, "onea.net-snmp.org") == 0) {
+            *addr_out = htonl(INADDR_LOOPBACK);
+            return 0;
+        } else if (strcmp(name, "twoa.net-snmp.org") == 0) {
+            *addr_out = htonl(INADDR_LOOPBACK + 1);
+            return 0;
+        } else if (strcmp(name, "no.such.address.") == 0) {
+            return -1;
+        }
+    }
+
+    {
 #if HAVE_GETADDRINFO
     struct addrinfo *addrs = NULL;
     struct addrinfo hint;
@@ -826,6 +844,7 @@ netsnmp_gethostbyname_v4(const char* name, in_addr_t *addr_out)
 #else /* HAVE_GETIPNODEBYNAME */
     return -1;
 #endif
+    }
 }
 
 int


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